Galvanized multi-tubular beam and method of continuously forming the same

ABSTRACT

A galvanized reinforcement beam is continuously formed by uncoiling a roll of galvanized sheet stock in a generally horizontal plane. Protrusions are formed at an upper surface of the sheet stock, which is then roll formed to form a tubular shape with the protrusions abutting a surface of the sheet stock to form venting gaps. The sheet stock is laser welded at the protrusions to continuously form a weld joint, where zinc oxide gas generated from the welding is permitted to escape an interior of the tubular shape through the venting gaps.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C § 119(e) to U.S.Provisional Patent Application No. 62/771,843, filed Nov. 27, 2018, andto U.S. Provisional Patent Application No. 62/812,684, filed Mar. 1,2019, the disclosures of these prior applications are considered part ofthis application and are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present disclosure relates to vehicle structural and reinforcementbeams and associated methods of roll form manufacturing and metalprocessing.

BACKGROUND

Vehicles are subjected to various tests that are mandated by governmentregulations and insurance certifications, such as tests for impactenergy management and absorption. The results of these tests may bedependent on various vehicle components and structural designs,including bumper assemblies and structural reinforcement beams. Morespecifically, test results can rely on both the cross-sectional geometryand weld quality of these beams.

It is known to galvanize or apply protective zinc coatings to steelcomponents of a vehicle to prevent rust or iron oxide from forming onthe steel components over time. It is also generally known that weldinggalvanized metal creates zinc oxide fumes when the zinc layer or coatingis burned off or evaporated from the steel component at or near the weldjoint from the high heat used in some forms of welding. The zinc oxidefumes generated during welding can be ventilated from an areasurrounding the weld joint, but if such fumes are not properlyventilated, they can be hazardous to operators and jeopardize thequality of the weld, such as if the zinc oxide penetrates the moltenmetal at a weld joint.

SUMMARY

The present disclosure provides a galvanized reinforcement beam and amethod of continuously forming the beam. Initially, a roll of galvanizedsheet stock may be uncoiled in a generally horizontal plane to beprocessed, such as by being uncoiled at a generally constant rate towardand into a roll former. The roll former is configured to form the sheetinto a beam with at least one longitudinally extending tubular portion.Either prior to entering the roll former or in-line on the roll former,protrusions are formed at a surface of the galvanized sheet stock. Theprotrusions may be formed by laser forming dimples with raised portionsat generally consistent intervals along a generally straight line on thesheet. When the sheet is roll formed, the protrusions interface withanother section of the metal sheet at a desired attachment seam thatencloses the tubular portion of the beam, such that the protrusions abuta surface of the opposing sheet stock to form venting gaps between theprotrusions. The sheet stock is laser welded along the protrusions tocontinuously form a weld joint, where zinc oxide gas that is generatedfrom the welding is permitted to escape an interior of the tubular shapethrough the venting gaps upstream the roll form line from the weld jointbeing formed. As the weld joint is formed, the molten metal generatedfrom welding may fill the venting gaps to close the tubular shape of thebeam. As such, the protrusions may result in the weld joint beinggenerally free of zinc gas pitting or pockets and may result in athickness at the weld joint that slightly separates the planar surfacesof the sheet stock adjacent to the weld joint.

According to one aspect of the present disclosure, a galvanizedmulti-tubular beam for a vehicle structure or a bumper reinforcement ismanufactured by roll forming a galvanized metal sheet to form twoadjacent tubular portions that share a common center wall of the beam.Outer sections of the metal sheet that form the two adjacent tubularportions extend from opposing sides of a center section of the metalsheet that forms the common center wall of the beam. The galvanizedmulti-tubular beam includes an edge portion of one of the outer sectionsof the galvanized metal sheet that is attached to the center section ofthe galvanized metal sheet at a weld joint. The weld joint has athickness that separates a planar surface of the edge portion from aplanar surface of the center section. The thickness of the weld joint isformed by a plurality of protrusions that protrude from the planarsurface of the outer section or the center section of the metal sheet,such that, when welding the weld joint, the longitudinal spacing betweenthe plurality of protrusions provides ventilation openings for zincoxide fumes generated from the welding to escape the interior of therespective tubular portion of the beam.

The protrusions formed on the sheet stock may be spaced at generallyconsistent intervals, where the weld joint interconnects theprotrusions. The weld joint may extend continuously along the beam toenclose the interior of the respective tubular portion of the beam. Theweld joint may be formed via laser welding, so as to form a narrow heataffect zone, such as an area of approximately between 1 mm and 2 mm.

According to another aspect of the present disclosure, a method ofcontinuously forming a galvanized reinforcement beam includes uncoilinga roll of galvanized sheet stock in a generally horizontal plane.Dimples are laser formed over an upper surface of the sheet stock at afirst laser head station as the galvanized sheet continuously movesthrough the first laser head station. The sheet stock is roll formedthrough a set of roll stations to form a tubular shape with an edgesection of the sheet stock in contact with an intermediate section ofthe sheet stock. The edge section and/or the intermediate section of thesheet stock includes the dimples, where the dimples form venting gapsbetween the edge section and the intermediate section of the sheetstock. The edge portion is laser welded to the intermediate portion ofthe sheet stock at a second laser head station to continuously form aweld joint, where zinc oxide gas generated from the welding is permittedto escape an interior of the tubular shape through the venting gaps.

According to yet another aspect of the present disclosure, a galvanizedmulti-tubular beam is manufactured by roll forming a galvanized metalsheet to form two adjacent tubular portions that share a common centerwall of the beam. The galvanized multi-tubular beam has an edge portionof an outer section of the galvanized metal sheet attached via a weldjoint to a reinforcement rib formed at center section of the galvanizedmetal sheet. The edge portion of the galvanized metal sheet forms thecommon center wall of the beam. The weld joint has a thickness thatseparates a planar surface of the edge portion from a planar surface ofthe reinforcement rib. The thickness of the weld joint is formed by aplurality of protrusions that protrude from the planar surface of atleast one of the edge portion or the reinforcement rib. When welding theweld joint, a longitudinal spacing between the protrusions providesventilation openings for zinc oxide fumes generated from the welding toescape an interior of the respective tubular portion of the beam.

According to yet a further aspect of the present disclosure, a method ofcontinuously forming a galvanized reinforcement beam includes uncoilinga roll of galvanized sheet stock in a generally horizontal plane. Thesheet stock is roll formed through a first roll station to form an opensection shape with an edge portion of the sheet stock spaced from anintermediate portion of the sheet stock. Dimples are formed over asurface of the edge portion and/or the intermediate portion of the sheetstock at a first laser head station as the galvanized sheet stockcontinuously moves through the first laser head station. The sheet stockin bent through a second roll station to form a tubular shape with theedge portion of the sheet stock in contact with the intermediate portionof the sheet stock. The dimples form venting gaps between the edgeportion and the intermediate portion of the sheet stock. The edgeportion is laser welded to the intermediate portion of the sheet stockat a second laser head station to continuously form a weld joint alongthe dimples, such that zinc oxide gas generated from the welding ispermitted to escape an interior of the tubular shape through the ventinggaps. Optionally, the second laser head station may be void of anyinternal mandrels disposed at an interior of the tubular shape.

These and other objects, advantages, purposes, and features of thepresent disclosure will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a bumper reinforcement beam supported bycrush cans at a vehicle frame in accordance with one or more embodimentsillustrated herein;

FIG. 2 is a cross-sectional view of the reinforcement beam along lineII-II in FIG. 1;

FIG. 2A is a cross-sectional view of an additional reinforcement beam;

FIG. 3 is a schematic elevational view of an apparatus configured tomanufacture the present reinforcement beam;

FIG. 4A is a series of cross sections labeled S1-S24, showing a shape ofthe metal sheet stock at various forming steps when roll forming thebeam of FIG. 2;

FIG. 4B is a further series of cross sections labeled S25-S46, showing ashape of the metal sheet stock at additional forming steps when rollforming the beam of FIG. 2;

FIG. 5A is a schematic perspective view of a laser station formingdimples over an upper surface of metal sheet stock;

FIG. 5B is an enlarged view of the formed dimples shown at section VB inFIG. 5A;

FIG. 5C is a cross-sectional view of a dimple shown along line VC-VC inFIG. 5B;

FIG. 6A is a perspective view of a section of the partially formed beamat forming step S25 of FIG. 4B;

FIG. 6B is a cross-sectional view of the partially formed beam of FIG.6A;

FIG. 6C is an enlarged view of the dimples shown at section VIC in FIG.6B;

FIG. 7A is a perspective view of a section of the partially formed beamat laser welding step S29 of FIG. 4B;

FIG. 7B is another perspective view of the section of the beam shown inFIG. 7A;

FIG. 7C is an enlarged view of the laser welding shown at section VIICin FIG. 7B;

FIG. 7D is a cross-sectional view of the section of the beam shown inFIG. 7A;

FIG. 7E is a cross-sectional view of the beam taken along the seam priorto being welded closed, taken along line VIIE-VIIE in FIG. 7D;

FIG. 7F is an enlarged view of the weld being formed at section VIIF inFIG. 7D;

FIG. 7G is an enlarged view of the post-formed weld of FIG. 7F, showinga narrow heat affect zone;

FIG. 8A is a perspective view of a section of the partially formed beamat forming step S37 of FIG. 4B;

FIG. 8B is a cross-sectional view of the partially formed beam of FIG.8A;

FIG. 9A is a perspective view of a section of the partially formed beamat laser welding step S46 of FIG. 4B;

FIG. 9B is a cross-sectional view of the section of the beam shown inFIG. 9A;

FIG. 10 is a cross-sectional view of an additional reinforcement beam;

FIG. 11 is a perspective view of an end section of the beam shown inFIG. 10;

FIG. 12A is a perspective view of a partially formed beam at a stage informing the reinforcement beam shown in FIG. 10;

FIG. 12B is a cross-sectional view of the partially formed beam of FIG.12A at a laser station that is forming dimples over an engagementsurface of the metal sheet;

FIG. 12C is a cross-sectional view of the partially formed beam of FIG.12B at a laser station that is welding an edge of the metal sheet to theengagement surface and enclosing a tubular portion of the reinforcementbeam;

FIG. 13A is a perspective view of the partially formed beam of FIG. 12Cwith the metal sheet further formed toward the shape of thereinforcement beam shown in FIG. 10;

FIG. 13B is a cross-sectional view of the partially formed beam of FIG.13A at a laser station that is forming dimples over another engagementsurface of the metal sheet;

FIG. 13C is a cross-sectional view of the formed reinforcement beam ofFIG. 10 at a laser station that is welding an edge of the metal sheet tothe engagement surface and enclosing a second tubular portion of thereinforcement beam;

FIG. 14 is a cross-sectional view of an additional reinforcement beam;

FIG. 15 is a perspective view of an end section of the beam shown inFIG. 14;

FIG. 16A is a perspective view of a partially formed beam at a stage informing the reinforcement beam shown in FIG. 14;

FIG. 16B is a cross-sectional view of the partially formed beam of FIG.16A at a laser station that is forming dimples over an engagementsurface of the metal sheet;

FIG. 16C is a cross-sectional view of the partially formed beam of FIG.16B at a laser station that is welding an edge of the metal sheet to theengagement surface and enclosing a tubular portion of the reinforcementbeam;

FIG. 17A is a perspective view of the partially formed beam of FIG. 16Cwith the metal sheet further formed toward the shape of thereinforcement beam shown in FIG. 14;

FIG. 17B is a cross-sectional view of the partially formed beam of FIG.17A at a laser station that is forming dimples over another engagementsurface of the metal sheet;

FIG. 17C is a cross-sectional view of the formed reinforcement beam ofFIG. 14 at a laser station that is welding an edge of the metal sheet tothe engagement surface and enclosing a second tubular portion of thereinforcement beam;

FIG. 18 is a cross-sectional view of yet an additional reinforcementbeam;

FIG. 19A is a cross-sectional view of a partially formed beam at a stagein forming the reinforcement beam shown in FIG. 18, showing a laserstation location for enclosing a tubular portion of the reinforcementbeam;

FIG. 19B is a cross-sectional view of the partially formed beam of FIG.19A with the metal sheet further formed toward the shape of thereinforcement beam shown in FIG. 18, showing another laser stationlocation for enclosing a second tubular portion of the reinforcementbeam;

FIG. 20 is a cross-sectional view of an additional reinforcement beam;

FIG. 20A is an enlarged view of a weld being formed at section XXA inFIG. 20;

FIG. 21 is a schematic perspective view of an example of protrusionsdisposed over an upper surface of metal sheet stock; and

FIG. 22 is a schematic perspective view of another example ofprotrusions disposed over an upper surface of metal sheet stock.

DETAILED DESCRIPTION

Referring now to the drawings and the illustrative embodiments depictedtherein, a galvanized beam 10 may be generally continuously formed witha roll forming process that has a method of continuously welding a seamor seams of the beam 10 closed in a manner that ventilates zinc oxidefumes generated within enclosed areas of the beam 10 when welding thegalvanized sheet stock used to form the beam 10. The galvanizedmulti-tubular beam 10 may be used for a vehicle structural reinforcementor a bumper reinforcement, such as shown in FIG. 1 where the beam 10 islongitudinally curved with varying degrees of curvatures in order tocorrespond with a bumper design of a particular vehicle. When used as abumper reinforcement, the beam 10 may be attached to crush cans disposedat the front of the vehicle frame so as to span across the width of thevehicle frame. Alternatively, the beam described herein may be adaptedfor various alternative structural or reinforcement applications,whether linear or curved, such as a rear bumper, a door impact beam, aframe member (e.g., a roof bow, a header, a pillar, a rocker rail, aseat member, or the like), and a frame member for a vehicle battery traysupport, among other conceivable vehicle and non-vehicle related membersand components.

The beam 10 may be manufactured by roll forming a galvanized metal sheet12, such as shown uncoiling from a roll in FIG. 3, to form two adjacenttubular portions 14, 16 that share a common center wall 18 of the beam10. The outer sections 12 a, 12 c of the metal sheet 12 that form thetwo adjacent tubular portions 14, 16 extend from opposing sides of acenter section 12 b of the metal sheet 12 that forms the common centerwall 18 of the beam, where such sections may be initially delineated atforming step S2 of FIG. 4A. Once the beam 10 is formed, the two adjacenttubular portions 14, 16 of the beam 10 are defined, such as oriented inFIGS. 1 and 2, by front walls 20, 22, rear walls 24, 26, an upper wall28, and a lower wall 30. The front walls 20, 22 of the adjacent tubularportions 14, 16 are substantially aligned with each other so as to forman outward facing or impact surface of the beam when used as a bumperreinforcement beam. Similarly, the rear walls 24, 26 are in generalalignment with each other and are substantially parallel with the frontwalls 20, 22. Further, the upper and lower walls 28, 30 aresubstantially parallel with each other and the center wall 18 andgenerally perpendicular with the front and rear walls 20, 22, 24, 26. Itis understood that additional embodiments of the beam may assume variousshapes and orientations from that shown in FIG. 2 and may includealternatively dimensional proportions, such as for differentapplications of the beam.

Referring now to FIG. 3, as the galvanized sheet stock 12 is uncoiledfrom the roll, protrusions 32 may be formed at an upper surface of thesheet stock 12, such as at a laser head station 31 ahead of the rollforming line. It is also contemplated that the protrusions mayalternatively be formed at a separate processing line from the rollforming line, such as by re-coiling the sheet after forming theprotrusions and then moving the coiled roll to the roll forming line.Alternatively, the protrusions may be formed inline or during the rollforming process, such as immediately prior to welding, so as to reducethe risk of the protrusions being deformed by the roll former stations.

The laser head station 31 shown in FIG. 3 may form the protrusions ordimples 32 at generally consistent intervals along a generally straightline longitudinally along in alignment with a length of the formed beam10. It is understood that the spacing or intervals between theprotrusions may vary along the beam. It is also conceivable that theprotrusions may be formed by alternative devices, for example, bydeforming the sheet mechanically, such as with a serrated disk, astamping device, or other conceivable means.

Furthermore, the protrusions may be disposed at the sheet withelectrospark deposition (ESD) (i.e., pulsed fusion surfacing or pulsedelectrode surfacing), such as shown in FIG. 21, where a pulsedmicro-welding process provides intermittent ESD material 33 disposed atand protruding from a planar surface of the galvanized metal sheet 12.These protrusions 33 likewise create ventilation openings for zinc oxidefumes generated from welding to escape the interior of the respectivetubular portion of the formed beam. Also, the protrusions may bedisposed at the sheet with additive manufacturing (i.e., 3D printing),such as shown in FIG. 22, where a solid material 35 (e.g., lasersintering or melting metal powder) is disposed at and protrudes from aplanar surface of the galvanized metal sheet 12. These protrusions 35likewise create ventilation openings for zinc oxide fumes generated fromwelding to escape the interior of the respective tubular portion of theformed beam.

The line of protrusions or dimples 32 are formed at a location on oralong the sheet 12 to correspond with the attachment point or weld seamwhen the sheet 12 is formed to close the corresponding tubular portionof the beam 10. As illustrated at step S1 of FIG. 4A, the laser headstation 31 may form dimples 32 at two locations with two separate laserbeams 34 or equivalents thereof, where the selected location of eachline of dimples 32 corresponds with a later-formed weld joint 36, 38 ofthe beam 10. These weld joints 36, 38 are formed at or along the dimples32 to enclose the interior areas of the respective adjacent tubularportions 14, 16 of the beam 10. As further illustrated in FIGS. 5A and5B, the two lines of dimples 32 are parallel with each other and havethe same general interval or spacing between each individual dimple 32longitudinally along the sheet 12.

The dimples 32 may each have a recessed portion 40 and a raised portion42, which may be formed from a laser pulsing or otherwise intermittentlycontacting the sheet 12 (i.e. laser dimpling). More specifically, thesheet material, laser intensity, and speed of the sheet 12 movingrelative to the laser beam 34 may be calibrated and configured so thatthe laser beam does not penetrate through the sheet and instead formsthe recessed portion 40 at a desired depth and the raised portions 42 ata corresponding desired height, such as shown in FIG. 5B. To do so, asmall pool of molten metal may be formed on the upper surface of thesheet 12 by the heat generated from the laser 34 contacting the sheet12. When the laser 34 stops or no longer contacts the sheet 12 (orotherwise sufficiently reduces intensity), the metal cools and hardenswith the raised portion 42 protruding at a height that extends beyondthe surrounding upper surface of the metal sheet 12, such as shown inFIG. 5C. The length of each dimple taken longitudinally along the lengthof the sheet may be approximately between 2 mm and 5 mm. It is alsocontemplated that the dimples may also or alternatively be formed at thebottom surface of the sheet, such as at a location so as to be disposedat the center section 12 b of the metal sheet that contacts the edgeportion of the outer section 12 a of the sheet 12.

With further reference to FIG. 3, a roll of galvanized sheet stock maybe uncoiled in a generally horizontal plane to be processed, such as bybeing uncoiled at a generally constant rate toward and into a rollformer or roll forming apparatus, such as with the laser station 31initially forming the protrusions or dimples 32 at the upper surface ofthe sheet 12. The galvanized multi-tubular beam 10 is then formed to itsshape by the roll forming apparatus processing the single sheet 12 via aseries of paired rolls in roll forming stations, with each stationperforming a forming operation, such as shown by the roll formed flowerpattern of forming steps S2-S28 and S30-S45 shown in FIGS. 4A and 4B.During the roll forming process, the metal sheet 12 is formed to havethe adjacent tubular portions 14, 16 formed on opposite sides of thesingle center wall 18. Again, it is contemplated that the beam formedwith the ventilation welding process may have an alternative profile orshape from that shown in FIG. 2, such as a B-shaped beam or a D-shapedbeam.

As shown in FIG. 3, the roll former may include a first series 44 offorming rolls in stations that successively bend the outer section 12 aof the sheet 12 and the center section 12 b of the sheet 12, such as tocorrespond to forming steps S2-S28 shown in FIGS. 4A and 4B. Thus, thefirst series 44 of forming rolls successively form the sheet 12 towardand into the shape of the corresponding tubular portion 14 of the beam10 and orient the center wall 18 of the beam 10 toward and into generalperpendicular orientation relative to the other outer section 12 c ofthe sheet 12. In doing so, an edge portion of the outer section 12 a ofthe metal sheet 12 is formed with a radiused end that is configured tocontact the center section 12 b of the metal sheet 12, such as shown atstep S25 illustrated in greater detail in FIGS. 6A and 6B. Accordingly,the first series 44 of forming rolls may deform slightly less than“half” of the width of the sheet in a first direction (illustrated as acounterclockwise direction in FIGS. 4A and 4B) to form a first tube ortubular portion with a radiused edge of the sheet abutted against aradiused end of a center wall. It is conceivable that the first seriesof forming rolls may include more or fewer stations so as to form thesheet from a flat section to generally provide a tubular portion with aventilation seam, as disclosed herein ready for welding the galvanizedsheet.

Prior to welding at a first laser welding station 46 (FIG. 3), the firstseries 44 of forming rolls may place the line of protrusions 32 on theouter section 12 a of the metal sheet 12 in contact with a generallyplanar surface of the sheet 12, such as shown in FIG. 7E. The line ofcontact of the protrusions 32 against the center section 12 b of thesheet 12 may be at an end of the center wall 18 where the center wall 18becomes generally planar or flat. The longitudinal spacing between theprotrusions 32 provides the ventilation openings 48 for zinc oxide fumesgenerated from welding to escape the interior of the respective tubularportion of the beam 10. The separation between the edge portion of theouter section 12 a and the center section 12 b that is provided by theprotrusions 32 is approximately between 50 micrometers and 300micrometers. As such, the line of protrusions shown in FIG. 7E is anexample of a ventilation seam configured for continuously laser weldinga galvanized sheet that is continuously roll formed to a tubular-shapedbeam. It is beneficial to ventilate the welding of galvanized steel,especially fumes trapped in an enclosed area of a tube, so as to have aconsistent weld free of gas openings or pockets that can form withpressured gases, such as zinc oxide gas.

As shown in FIGS. 7A-7F, the weld joint 36 is formed via laser weldingalong the ventilation seam at the first welding station 46 to form theweld joint 36 that is closed continuously along the length of the beam10. Due to the protrusions 32 that form the ventilation openings 48, theweld joint 36 has a thickness (of approximately between 50 micrometersand 300 micrometers) that slightly separates a planar surface of theedge portion of the outer section 12 a from a planar surface of thecenter section 12 b. When welding the weld joint 36, the longitudinalspacing between the protrusions 32 provides the ventilation openings 48for zinc oxide fumes 50 generated from the welding to escape theinterior of the tubular portion 14 of the beam 10 upstream in the rollformer from the welding station 46 (i.e. prior to the ventilationopenings 20 being welded closed at the welding station 46).

As shown at FIG. 7D, the laser beam 52 that is generated by the weldingstation 46 to form the weld joint 36 is positioned approximatelyperpendicular to the orientation of the center wall 18. Thissubstantially perpendicular orientation of the laser beam 52 furtherforms the weld joint 36 with a relatively narrow heat affect zone 54,such as shown in FIG. 7G. The heat affect zone 54 may, for example, beapproximately between 1 mm and 2 mm.

Accordingly, when the outer section 12 c of the sheet 12 is generallyperpendicular to the center wall section 12 b, the location of the weldjoint 36 is balanced with the presence and depth of a stiffening rib 56formed in the front wall 22 of the second tubular portion 16 of the beam10. In an alternative embodiment, as shown in FIG. 2A, a beam 110 issimilarly formed, but the outer section 112 c of the sheet 112 does nothave a stiffening rib, so as to allow for a more perpendicularorientation of a laser welder when welding the weld joint 136 along thelength of the beam 110.

Referring again to FIG. 4B, after forming the weld joint 36, the sheet12 continues into a second series 58 of forming rolls in stations thatsuccessively bend the remaining outer section 12 c of the sheet 12, suchas to correspond to forming steps S30-S45. Thus, the second series 58 offorming rolls successively form the sheet 12 toward and into the shapeof the corresponding tubular portion 16 of the beam 10, generallycompleting the shape of the beam 10. In doing so, an edge portion of theouter section 12 c of the metal sheet 12 is configured to contact andform a lap joint with the rear wall 24 of the first tubular portion 14of the beam 10, such as shown at step S37 illustrated in greater detailin FIGS. 8A and 8B. The lap joint includes a thickness that separates aplanar surface of the edge portion from a planar surface of the rearwall 24, where the thickness of the weld joint is formed by theprotrusions 32 that protrude from the planar surface of the rear wall 24(and/or the edge portion), such that when welding the lap joint, zincoxide fumes 50 escape the interior of the respective tubular portion 16of the beam through vent openings 48 formed by the protrusions 32. Theseparation between the edge portion of the outer section 12 c and therear wall 24 that is provided by the protrusions 32 is approximatelybetween 50 micrometers and 300 micrometers. Accordingly, the secondseries 58 of forming rolls may deform the remaining “half” of the widthof the sheet in the same rotational direction as the first series offorming rolls (illustrated as a counterclockwise direction in FIGS. 4Aand 4B) to form a second tube or tubular portion. It is againconceivable that the second series of forming rolls may include more orfewer stations to generally provide a tubular portion with a ventilationseam, as disclosed herein ready for welding the galvanized sheet.

The second series 58 of forming rolls, such as shown in FIG. 3, mayplace the end of the outer section 12 c of the metal sheet 12 in contactwith a recessed area 60 formed along the rear wall 24, as shown in FIG.9A. The recessed area 60 on the rear wall 24 may provide an area for asecond line of protrusions 32. The recessed area 60 allows the rearwalls 24, 26 of the beam to be disposed in generally planar alignmentwith each other. The longitudinal spacing between the protrusions 32again provides the ventilation openings 48 for zinc oxide fumesgenerated from welding to escape the interior of the respective tubularportion of the beam 10. As such, the line of protrusions shown in FIG.9A is another example of a ventilation seam configured for continuouslylaser welding a galvanized sheet that is continuously roll formed to atubular-shaped beam.

As further shown in FIGS. 9A and 9B, the weld joint 38 is formed vialaser welding along the ventilation seam at a second welding station 64(FIG. 3) to form the weld joint 38 that is closed continuously along thelength of the beam 10. Due to the protrusions 32 that form theventilation openings 48, the weld joint 38 has a thickness that slightlyseparates a planar surface of the edge portion of the outer section 12 cfrom the planar surface of the sheet that it contacts. When welding theweld joint 38, the longitudinal spacing between the protrusions 32provides the ventilation openings 48 for zinc oxide fumes 50 generatedfrom the welding to escape the interior of the tubular portion 16 of thebeam 10 upstream in the roll former from the welding station 64. Asshown at FIG. 9B, the laser beam 66 that is generated by the weldingstation 64 to form the weld joint 38 is positioned approximatelyperpendicular to the orientation of the rear walls 24, 26. Again, thissubstantially perpendicular orientation of the laser beam 66 allows theweld joint 38 to be formed with a relatively small heat affect zone.

The roll former may further be configured to form channel or stiffeningribs 56 that protrude into an interior volume of each tubular portion14, 16, such as shown at the front walls of the beam. The stiffeningribs 56 (i.e. an inwardly formed depression, also sometimes called a“power rib”) further stiffens the wall section, and accordingly, in thebeam 10 shown in FIG. 2 stiffens the front face of the beam 10 andstiffens the corresponding tube portions 14, 16. The illustratedstiffening ribs 56 have a width diameter about 10%-40% of a width of thecorresponding wall section (or more preferably about 20%-30% of thewidth) and has a depth about equal to its width diameter. The bottoms ofthe illustrated channel ribs are semicircular shaped. Nonetheless, it iscontemplated that a depth and size of the channel ribs can be madeshallow, deeper, wider, narrower, flat-bottomed, or otherwise modifiedto satisfy specific functional requirements of a beam.

The beam 10 is made from a sheet 12 of steel material having a thicknessof 0.8 mm to 1.4 mm or approximately between 1 mm and 1.5 mm. Also, thesheet 12 may have a tensile strength of about 800 to 2000 MPa (i.e.about 120 to 290 ksi). The illustrated beam is about 80 mm high and 40mm deep (in vehicle-mounted position), with two channel ribs beingformed in the beam's front face (one over each tube). Each illustratedstiffening rib is about 8 mm to 10 mm deep and 8 mm to 10 mm wide, andincludes a rounded bottom. However, it is contemplated that the presentbeam can be made of different materials, including AHSS (Advanced HighStrength Steels) and that it can be made from a sheet having a thicknessof about 0.8 mm to 3.0 mm thick (or such as 0.8 mm to 1.4 mm thickness),and can be made in different beam cross-sectional sizes, such as about80 mm to 150 mm high, and 30 mm to 60 mm deep, and having a length equalto or slightly greater than a distance between vehicle mounts/bumperframe rail tips.

A related apparatus for manufacturing a tubular reinforcement beam 10 ona roll former comprises an in-line sweep station 68 and cutoff 70. Thefirst and second laser welding stations 46, 64 are configured to formwelds along the beam that are capable of withstanding longitudinalbending of the beam at the in-line sweep station 68. It is understoodthat the laser beams of the laser welding stations 46, 64 may bepositioned at various orientations relative to the beam as necessary toform the desired weld, such as above, below, or at a side of the beam.It is further noted that the roller former can utilize a roll mill withhorizontal axes supporting forming rolls, or alternatively can utilize aroll mill with vertical axes supporting forming rolls.

Referring now to FIGS. 10-13C, an additional example of a galvanizedmulti-tubular beam 210 is shown having two adjacent tubular portions214, 216 that share a common center wall 218 of the beam 210. Differentfrom the beam 10 shown in FIG. 2, an outer section 272 of the metalsheet 212 forms the common center wall 218 of the beam 210, opposed to acenter section of the sheet. The center wall 218 of the beam 210 shownin FIG. 10 is formed by an edge portion 272 a of the outer section 272of the metal sheet 212 attaching at an inner landing surface 274 of thebeam 210 to enclose one of the tubular portions 214. The other tubularportion 216 is formed by the opposing outer section 276 of the metalsheet being formed in an opposite rotational direction from the firsttubular portion 214 so that an edge portion 276 a of the outer section276 of the metal sheet 212 is attached to an opposing end of the centerwall 218 with a lap joint 238 similar to that shown at the weld joint 38of the beam 10 shown in FIG. 2.

The formed beam 210 shown in FIGS. 10 and 11 may be rotated about itslongitudinal axis to be oriented similar to the beam 10 shown in FIG. 2,such as for use as a bumper reinforcement beam, whereby the respectivewalls of the beam 210 may be referenced as front walls 220, 222, rearwalls 224, 226, an upper wall 228, and a lower wall 230. The front walls220, 222 of the adjacent tubular portions 214, 216 are substantiallyaligned with each other so as to form an outward facing or impactsurface of the beam when used as a bumper reinforcement beam. Similarly,the rear walls 224, 226 are in general alignment with each other and aresubstantially parallel with the front walls 220, 222. Further, the upperand lower walls 228, 230 are substantially parallel with each other andthe center wall 218 and generally perpendicular with the front and rearwalls 220, 222, 224, 226. It is understood that additional examples ofthe beam 210 may assume various orientations from that shown in FIGS. 10and 11 and may include alternative cross-sectional shapes anddimensional proportions, such as for different uses and applications ofthe beam.

Referring now to FIG. 12A, the galvanized sheet stock 212 may be rollformed through a series of roll dies to form a cross-sectional shape,such as the illustrated example, that is achieved prior to closing theseam that is welded to enclose the first tubular portion 214 (FIG. 10).In this illustrated example, the protrusions 232 (FIG. 12B) that areformed at the seam are formed in-line on the roll former after passingthrough several roll form dies on the roll form line. By roll formingthe sheet stock 212 to achieve an intermediate cross-sectional shape ofthe beam 210 prior to forming protrusions 232, the protrusions can thenbe formed without a risk of being damaged or flattened from passingthrough roll form dies prior to being utilized at the weld seam.Specifically, as shown in FIG. 12A, the outer edge portion 272 a of thesheet 212 that is used to form the first tubular portion 214 of the beam210 is spaced upward and away from the desired landing surface 274 ofthe sheet to allow a laser beam 234 to linearly access the landingsurface 274 of the sheet 212 to form protrusions 232 (FIG. 12B).

As further shown in FIG. 12A, the rear corner 278 of the tubular portion214 on the opposing side of the tubular portion 214 from the landingsurface 274 that is used to form the desired weld joint may be used as asingle articulation point on the sheet. The sheet may be bent about therear corner 278 to rotate the edge portion 272 a of the sheet down intoabutting engagement with the protrusions 232 formed at the landingsurface 274, as shown in FIG. 12C. Accordingly, as shown in FIG. 12A,the cross-sectional shape may be formed to have essentially all desiredshapes and formations of the first tubular portion 214 made in the outersection 272 of the metal sheet prior to forming the protrusions 232,such that only a final additional bend is needed at the rear corner 278to close and complete the shape of the first tubular portion 214. It isalso contemplated that additional or alternative articulation points maybe utilized on another example of the beam from that shown in FIGS.12A-12C, such as a beam with an alternative cross-sectional shape orroll forming sequence.

The protrusions 232 may be formed at a surface that corresponds with aportion of the sheet 212 that is desired to have a weld joint, such asat the landing surface 274 of the formed metal sheet 212 shown in FIG.12B. The protrusions 232 may be formed when the metal sheet continuouslypasses through a laser head station that is arranged in-line on the rollformer, between roll form dies. The protrusions 232 formed in-line onthe roll former may be disposed at generally consistent intervalslinearly along a longitudinal extent of the sheet 212 and may otherwisebe formed in the same or similar manner to those shown in FIGS. 5A-5Cand described above.

To form the protrusions 232, the laser beam 234 may be angled at anearly perpendicular orientation relative to the landing surface 274. Asshown in FIG. 12B, the landing surface 274 is disposed at a side portionof a stiffening rib 256 that is formed in the front wall 220 of the beam210. The stiffening ribs 256 protrude into an interior volume of eachtubular portion 214, 216 so as to stiffen the wall section of the beam210. Again, it is contemplated that a depth and size of the stiffeningribs can be altered from that illustrated in FIGS. 10-13C, such as tomake the ribs shallower, deeper, wider, narrower, or otherwise modifiedto satisfy specific functional requirements of the beam. Accordingly,the other stiffening rib 256 that is formed in outer section 276 of themetal sheet 212 used to form the second tubular portion 216 of the beam10 (FIGS. 10-11) may have a depth that is configured to allow for thegenerally perpendicular orientation of the laser beams 234, 252 whenforming the protrusions 232 and to corresponding weld joint 236.

Prior to welding the seam of the first tubular portion 214 of the beam210, one or more forming rolls may further form the outer section 272 ofthe metal sheet 212 to bend and rotate the edge portion 272 a about therear corner 278 and place the outer edge 272 a in contact with the lineof protrusions 232 on the landing surface 274 of the stiffening rib 256,as shown in FIG. 12C. The line of contact of the protrusions 232 againstthe edge portion 272 a of the metal sheet 212 provides longitudinalspacing between the protrusions 232 that create ventilation openings forzinc oxide fumes generated from welding to escape the interior of therespective tubular portion 214 of the beam 210. The separation betweenthe planar portions of the sheet created by the protrusions 232 isapproximately between 50 micrometers and 300 micrometers. Theprotrusions 232, thus, form a ventilation seam configured forcontinuously laser welding the galvanized sheet that is continuouslyroll formed to a tubular-shaped beam 210. The ventilation openings allowfumes that would otherwise be trapped in an enclosed area of a tube tofreely escape, so as to have a consistent weld that is free of gasopenings or pockets that can form with pressured gases, such as zincoxide gas.

With the outer portion 272 a near or in engagement with the landingsurface 274, the metal sheet 212 may enter a welding station that mayuse external mandrels to hold the shape of cross-section for welding,but otherwise be free of internal mandrels due to the cross-sectionalshape of the first tubular portion 214. The external mandrels may applyforce to the walls surrounding the first tubular portion 214 generallywithout disturbing the contact between the protrusions 232 and thelanding surface 274 and the generally perpendicular orientation of thecenter wall 218 relative the front and rear walls 220, 224 of the firsttubular portion 214. Specifically, opposing mandrels that apply force tothe front and rear walls 220, 224 do not disturb the orthogonal shape ofthe tubular portion 214 due to the distal end 272 b of the edge portion272 a being positioned at the start of a curved formation 280 on thestiffening rib 256 that transitions back to the front wall 220, wherebythe external mandrels in combination with the curved formation 280prevents movement of the distal end 272 b that would cause shearingforces at the weld joint 236. The resulting reduction or illumination ofinternal mandrels in the roll former can assist to reduce friction atthe surface of the metal sheet, which can undesirably cause thegalvanized coating the wear off.

As shown in FIG. 12C, the weld joint 236 is formed via laser weldingalong the ventilation seam so as to provide a seam that is attached andclosed continuously along the length of the beam 210. Due to theprotrusions 232 that form the ventilation openings, the weld joint 236may have a thickness, such as approximately between 50 micrometers and300 micrometers, which slightly separates a planar surface of the edgeportion 272 a of the outer section 272 from a planar surface of thelanding surface 274. When welding the weld joint 236, the longitudinalspacing between the protrusions 232 provides the ventilation openingsfor zinc oxide fumes 250 generated from the welding to escape theinterior of the tubular portion 214 of the beam 210 upstream in the rollformer from the welding station. As shown at FIG. 12C, the laser beam252 that is generated by the welding station to form the weld joint 236is positioned approximately perpendicular to the orientation of thecenter wall 218. This substantially perpendicular orientation of thelaser beam 252 further forms the weld joint 236 with a relatively narrowheat affect zone, such as approximately between 1 mm and 2 mm as shownin FIG. 7G.

After forming the weld joint 236, the sheet 212 continues into a secondseries of forming rolls in stations that successively bend the otherouter section 276 of the sheet 212 toward the shape of the secondtubular portion 216 of the beam 210. As shown in FIG. 13A, thecross-sectional shape is again formed near, but prior to closing a seamof a tubular portion of the beam 210. At the intermediatecross-sectional shape shown in FIGS. 13A and 13B, the protrusions 232are again formed at the seam in-line on the roll former so as to reducerisk of damaging or flattening the protrusions. Specifically, as shownin FIG. 13A, the outer edge portion 276 a of the sheet 212 that is usedto form the second tubular portion 216 of the beam 210 is spaced upwardand away from the desired landing surface 282 of the sheet to allow alaser beam 284 to linearly access the landing surface 282 of the sheet212 to form protrusions 232. The example shown in FIGS. 10-13C shows thelanding surface 282 used to form the laser welded lap joint 238 at arecessed area 260 formed along the rear wall 224 at a corner of thefirst tubular portion 214 adjacent to the center wall 218.

As further shown in FIG. 13A, the rear corner 286 of the second tubularportion 216 on the opposing side of the tubular portion 216 from theweld joint 236 may be used as a single articulation point on the sheet.The sheet may be bent about the rear corner 286 to rotate the edgeportion 276 a of the sheet down into abutting engagement with theprotrusions 232 formed at the landing surface 282, as shown in FIG. 13C.Accordingly, as shown in FIG. 13A, the cross-sectional shape may beformed to have essentially all desired shapes and formations of thesecond tubular portion 216 made in the outer section 276 of the metalsheet prior to forming the protrusions 232 on the landing surface 282,such that only a final additional bend is needed at the rear corner 286to close and complete the shape of the second tubular portion 216. It isalso contemplated that additional or alternative articulation points maybe utilized on another example of the beam from that shown in FIGS.13A-13C, such as a beam with an alternative cross-sectional shape orroll forming sequence.

As shown in FIG. 13B, the protrusions 232 may be formed when the metalsheet continuously passes through a laser head station that is arrangedin-line on the roll former, between roll form dies. The protrusions 232shown in FIG. 13B may again otherwise be formed in the same or similarmanner to those shown in FIGS. 5A-5C and described above. To form theprotrusions 232, the laser beam 284 may be angled at a nearlyperpendicular orientation relative to the landing surface 282.Similarly, the laser beam 266 used when forming the corresponding weldjoint 236 may be substantially perpendicular to the landing surface 282.

Prior to welding the seam of the second tubular portion 216 of the beam210, one or more forming rolls may further form the outer section 276 ofthe metal sheet 212 to bend and rotate the edge portion 276 a about therear corner 286 and place the outer edge 276 a in contact with the lineof protrusions 232 on the landing surface 282 in the recessed area 260,as shown in FIG. 13C. The recessed area 260 allows the rear walls 224,226 of the beam 210 to be disposed in generally planar alignment witheach other. The line of contact of the protrusions 232 against the edgeportion 276 a of the metal sheet 212 provides longitudinal spacingbetween the protrusions 232 that create ventilation openings for zincoxide fumes generated from welding to escape the interior of therespective tubular portion 216 of the beam 210. The separation betweenthe planar portions of the sheet created by the protrusions 232 isapproximately between 50 micrometers and 300 micrometers. Theprotrusions 232, thus, form a ventilation seam configured forcontinuously laser welding the galvanized sheet that is continuouslyroll formed to a tubular-shaped beam 210. The ventilation openings allowfumes that would otherwise be trapped in an enclosed area of a tube tofreely escape, so as to have a consistent weld that is free of gasopenings or pockets that can form with pressured gases, such as zincoxide gas.

With the outer portion 276 a near or in engagement with the landingsurface 282, the metal sheet 212 may enter a welding station that mayuse external mandrels to hold the shape of cross-section for weldingwith a laser beam 266, but otherwise be free of internal mandrels due tothe position of the weld joint at a lap joint unaffected by externalmandrel forces applied around the beam 212. As shown in FIG. 13C, thelaser welded lap joint 238 includes a thickness that separates a planarsurface of the edge portion from a planar surface of the rear wall 224,where the thickness of the weld joint 238 is formed by the protrusions232 that protrude from the planar surface of the rear wall 224 (and/orthe edge portion), such that when welding the lap joint, zinc oxidefumes 250 escape the interior of the respective tubular portion 216 ofthe beam through vent openings formed by the protrusions 232.Accordingly, to form a second tubular portion 216, the forming rolls maydeform the remaining section 276, such as slightly less than “half” ofthe width of the sheet, in the opposite rotational direction from theforming rolls that formed the first tubular portion 214.

The beam 210 is made from a sheet 212 of steel material having athickness of 0.8 mm to 1.4 mm or approximately between 1 mm and 1.5 mm.Also, the sheet 212 may have a tensile strength of about 800 to 2000 MPa(i.e. about 120 to 290 ksi). However, it is contemplated that thepresent beam can be made of different materials, including AHSS(Advanced High Strength Steels) and that it can be made from a sheethaving a thickness of about 0.8 mm to 3.0 mm thick (or such as 0.8 mm to1.4 mm thickness), and can be made in different beam cross-sectionalsizes, such as about 80 mm to 150 mm high, and 30 mm to 60 mm deep, andhaving a variable sized length for the desired application.

Referring now to FIGS. 14-17C, an additional example of a galvanizedmulti-tubular beam 310 is shown having two adjacent tubular portions314, 316 that share a common center wall 318 of the beam 310. Differentfrom the beam 10 shown in FIG. 2, both weld joints 336, 338 are formedas lap joints. The laser welded lap joints 336, 338 of the beam 310shown in FIG. 14 are formed in recessed areas to allow the respectivefront walls 320, 322 and rear walls 324, 326 of the beam 310 to bedisposed in generally planar alignment with each other, similar to thatshown at the weld joint 38 of the beam 10 shown in FIG. 2.

The formed beam 310 shown in FIGS. 14 and 15 may be rotated about itslongitudinal axis to be oriented similar to the beam 10 shown in FIG. 2,such as for use as a bumper reinforcement beam, whereby the respectivewalls of the beam 310 may be referenced as front walls 320, 322, rearwalls 324, 326, an upper wall 328, and a lower wall 330. The front walls320, 322 of the adjacent tubular portions 314, 316 are substantiallyaligned with each other so as to form an outward facing or impactsurface of the beam when used as a bumper reinforcement beam. Similarly,the rear walls 324, 326 are in general alignment with each other and aresubstantially parallel with the front walls 320, 322. Further, the upperand lower walls 328, 330 are substantially parallel with each other andthe center wall 318 and generally perpendicular with the front and rearwalls 320, 322, 324, 326. It is understood that additional examples ofthe beam 310 may assume various orientations from that shown in FIGS. 14and 15 and may include alternative cross-sectional shapes anddimensional proportions, such as for different uses and applications ofthe beam.

Referring now to FIG. 16A, the galvanized sheet stock 312 may be rollformed through a series of roll dies to form a cross-sectional shape,such as the illustrated example, that is achieved prior to closing theseam that is welded to enclose the first tubular portion 314 (FIG. 14).In this illustrated example, the protrusions 332 (FIG. 16B) that areformed at the seam are formed in-line on the roll former after passingthrough several roll form dies on the roll form line. By roll formingthe sheet stock 312 to achieve an intermediate cross-sectional shape ofthe beam 310 prior to forming protrusions 332, the protrusions can thenbe formed without a risk of being damaged or flattened from passingthrough roll form dies prior to being utilized at the weld seam.Specifically, as shown in FIG. 16A, the outer edge portion 372 a of thesheet 312 that is used to form the first tubular portion 314 of the beam310 is spaced downward and away from the desired landing surface 374 ofthe sheet to allow a laser beam 334 to linearly access the landingsurface 374 of the sheet 312 to form protrusions 332 (FIG. 16B).

As further shown in FIG. 16A, the front corner 388 of the tubularportion 314 may be used as a single articulation point on the sheetafter the protrusions 332 are formed. The sheet may be bent about thefront corner 388 to rotate the edge portion 372 a of the sheet up intoabutting engagement with the protrusions 332 formed at the landingsurface 374, as shown in FIG. 16C. Accordingly, as shown in FIG. 16A,the cross-sectional shape may be formed to have essentially all desiredshapes and formations of the first tubular portion 314 made in the outersection 372 of the metal sheet prior to forming the protrusions 332,such that only a final additional bend is needed at the front corner 388to close and complete the shape of the first tubular portion 314. It isalso contemplated that additional or alternative articulation points maybe utilized on another example of the beam from that shown in FIGS.16A-16C, such as a beam with an alternative cross-sectional shape orroll forming sequence.

The protrusions 332 may be formed at a surface that corresponds with aportion of the sheet 312 that is desired to have a weld joint, such asat the landing surface 374 of the formed metal sheet 312 shown in FIG.16B. The landing surface 374 used to form the laser welded lap joint 336is deposed at a recessed area 390 formed along the front wall 322 at acorner of the second tubular portion 316 adjacent to the center wall318. The protrusions 332 may be formed when the metal sheet continuouslypasses through a laser head station that is arranged in-line on the rollformer, between roll form dies. To form the protrusions 332, the laserbeam 334 may be angled at a nearly perpendicular orientation relative tothe landing surface 374. The protrusions 332 formed in-line on the rollformer may be disposed at generally consistent intervals linearly alonga longitudinal extent of the sheet 312 and may otherwise be formed inthe same or similar manner to those shown in FIGS. 5A-5C and describedabove.

Prior to welding the seam of the first tubular portion 314 of the beam310, one or more forming rolls may further form the outer section 372 ofthe metal sheet 312 to bend and rotate the edge portion 372 a about thefront corner 388 and place the outer edge 372 a in contact with the lineof protrusions 332 on the landing surface 374, as shown in FIG. 16C. Theline of contact of the protrusions 332 against the edge portion 372 a ofthe metal sheet 312 provides longitudinal spacing between theprotrusions 332 that create ventilation openings for zinc oxide fumes350 generated from welding to escape the interior of the respectivetubular portion 314 of the beam 310 (FIG. 16C). The separation betweenthe planar portions of the sheet created by the protrusions 332 isapproximately between 50 micrometers and 300 micrometers.

With the outer portion 372 a near or in engagement with the landingsurface 374, the metal sheet 312 may enter a welding station that mayuse external mandrels to hold the shape of cross-section for welding,but otherwise be free of internal mandrels due to the cross-sectionalshape of the first tubular portion 314. As shown in FIG. 16C, the weldjoint 336 is formed via laser welding along the ventilation seam so asto provide a seam that is attached and closed continuously along thelength of the beam 310. Due to the protrusions 332 that form theventilation openings, the weld joint 336 may have a thickness, such asapproximately between 50 micrometers and 300 micrometers, which slightlyseparates a planar surface of the edge portion 372 a of the outersection 372 from a planar surface of the landing surface 374. Whenwelding the weld joint 336, the longitudinal spacing between theprotrusions 332 provides the ventilation openings for zinc oxide fumes350 generated from the welding to escape the interior of the tubularportion 314 of the beam 310 upstream in the roll former from the weldingstation. As shown at FIG. 16C, the laser beam 352 that is generated bythe welding station to form the weld joint 336 is positionedapproximately perpendicular to the orientation of the center wall 318.This substantially perpendicular orientation of the laser beam 352further forms the weld joint 336 with a relatively narrow heat affectzone, such as approximately between 1 mm and 2 mm as shown in FIG. 7G.

After forming the weld joint 336, the sheet 312 continues into a secondseries of forming rolls in stations that successively bend the otherouter section 376 of the sheet 312 toward the shape of the secondtubular portion 316 of the beam 310. As shown in FIG. 17A, thecross-sectional shape is again formed near, but prior to closing a seamof a tubular portion of the beam 310. At the intermediatecross-sectional shape shown in FIGS. 17A and 17B, the protrusions 332are again formed at the seam in-line on the roll former so as to reducerisk of damaging or flattening the protrusions. Specifically, as shownin FIG. 17A, the outer edge portion 376 a of the sheet 312 that is usedto form the second tubular portion 316 of the beam 310 is spaced upwardand away from the desired landing surface 382 of the sheet to allow alaser beam 384 to linearly access the landing surface 382 of the sheet312 to form protrusions 332. The example shown in FIGS. 14-17C shows thelanding surface 382 used to form the laser welded lap joint 338 at arecessed area 360 formed along the rear wall 324 at a corner of thefirst tubular portion 314 adjacent to the center wall 318.

As further shown in FIG. 17A, the rear corner 386 of the second tubularportion 316 on the opposing side of the tubular portion 316 from theweld joint 336 may be used as a single articulation point on the sheet.The sheet may be bent about the rear corner 386 to rotate the edgeportion 376 a of the sheet down into abutting engagement with theprotrusions 332 formed at the landing surface 382, as shown in FIG. 17C.Accordingly, as shown in FIG. 17A, the cross-sectional shape may beformed to have essentially all desired shapes and formations of thesecond tubular portion 316 made in the outer section 376 of the metalsheet prior to forming the protrusions 332 on the landing surface 382,such that only a final additional bend is needed at the rear corner 386to close and complete the shape of the second tubular portion 316. It isalso contemplated that additional or alternative articulation points maybe utilized on another example of the beam from that shown in FIGS.17A-17C, such as a beam with an alternative cross-sectional shape orroll forming sequence.

As shown in FIG. 17B, the protrusions 332 may be formed when the metalsheet continuously passes through a laser head station that is arrangedin-line on the roll former, between roll form dies. The protrusions 332shown in FIG. 17B may again otherwise be formed in the same or similarmanner to those shown in FIGS. 5A-5C and described above. To form theprotrusions 332, the laser beam 384 may be angled at a nearlyperpendicular orientation relative to the landing surface 382.Similarly, the laser beam 366 used when forming the corresponding weldjoint 336 may be substantially perpendicular to the landing surface 382.

Prior to welding the seam of the second tubular portion 316 of the beam310, one or more forming rolls may further form the outer section 376 ofthe metal sheet 312 to bend and rotate the edge portion 376 a about therear corner 386 and place the outer edge 376 a in contact with the lineof protrusions 332 on the landing surface 382 in the recessed area 360,as shown in FIG. 17C. The recessed area 360 allows the rear walls 324,326 of the beam 310 to be disposed in generally planar alignment witheach other. The line of contact of the protrusions 332 against the edgeportion 376 a of the metal sheet 312 provides longitudinal spacingbetween the protrusions 332 that create ventilation openings for zincoxide fumes generated from welding to escape the interior of therespective tubular portion 316 of the beam 310. The separation betweenthe planar portions of the sheet created by the protrusions 332 isapproximately between 50 micrometers and 300 micrometers. Theprotrusions 332, thus, form a ventilation seam configured forcontinuously laser welding the galvanized sheet that is continuouslyroll formed to a tubular-shaped beam 310. The ventilation openings allowfumes that would otherwise be trapped in an enclosed area of a tube tofreely escape, so as to have a consistent weld that is free of gasopenings or pockets that can form with pressured gases, such as zincoxide gas.

With the outer portion 376 a near or in engagement with the landingsurface 382, the metal sheet 312 may enter a welding station that mayuse external mandrels to hold the shape of cross-section for weldingwith a laser beam 366, but otherwise be free of internal mandrels due tothe position of the weld joint at a lap joint unaffected by externalmandrel forces applied around the beam 312. As shown in FIG. 17C, thelaser welded lap joint 338 includes a thickness that separates a planarsurface of the edge portion from a planar surface of the rear wall 324,where the thickness of the weld joint 338 is formed by the protrusions332 that protrude from the planar surface of the rear wall 324 (and/orthe edge portion), such that when welding the lap joint, zinc oxidefumes 350 escape the interior of the respective tubular portion 316 ofthe beam through vent openings formed by the protrusions 332.Accordingly, to form a second tubular portion 316, the forming rolls maydeform the remaining section 376, such as slightly less than “half” ofthe width of the sheet, in the opposite rotational direction from theforming rolls that formed the first tubular portion 314.

The beam 310 is made from a sheet 312 of steel material having athickness of 0.8 mm to 1.4 mm or approximately between 1 mm and 1.5 mm.Also, the sheet 312 may have a tensile strength of about 800 to 2000 MPa(i.e. about 120 to 290 ksi). However, it is contemplated that thepresent beam can be made of different materials, including AHSS(Advanced High Strength Steels) and that it can be made from a sheethaving a thickness of about 0.8 mm to 3.0 mm thick (or such as 0.8 mm to1.4 mm thickness), and can be made in different beam cross-sectionalsizes, such as about 80 mm to 150 mm high, and 30 mm to 60 mm deep, andhaving a variable sized length for the desired application.

Referring now to FIGS. 18-19B, an additional example of a galvanizedmulti-tubular beam 410 is shown having two adjacent tubular portions414, 416 that share a common center wall 418 of the beam 410. The beam410 has a laser welded lap joint 436 formed in a recessed area to allowthe rear walls 424, 426 of the beam 410 to be disposed in generallyplanar alignment with each other. The beam 410 also has a weld joint 438formed in the seam between the center wall 418 and the front wall 422 toenclose the second tubular portion 416.

The formed beam 410 shown in FIG. 18 may be rotated about itslongitudinal axis to be oriented similar to the beam 10 shown in FIG. 2,such as for use as a bumper reinforcement beam, whereby the respectivewalls of the beam 410 may be referenced as front walls 420, 422, rearwalls 424, 426, an upper wall 428, and a lower wall 430. The front walls420, 422 of the adjacent tubular portions 414, 416 are substantiallyaligned with each other so as to form an outward facing or impactsurface of the beam when used as a bumper reinforcement beam. Similarly,the rear walls 424, 426 are in general alignment with each other and aresubstantially parallel with the front walls 420, 422. Further, the upperand lower walls 428, 430 are substantially parallel with each other andthe center wall 318 and generally perpendicular with the front and rearwalls 420, 422, 424, 426. It is understood that additional examples ofthe beam 410 may assume various orientations from that shown in FIG. 18and may include alternative cross-sectional shapes and dimensionalproportions, such as for different uses and applications of the beam.

Referring now to FIG. 19A, the galvanized sheet stock 412 may be rollformed through a series of roll dies to form a cross-sectional shape, asshown in solid lines, that is achieved prior to closing the seam that iswelded to enclose the first tubular portion 414 (FIG. 18). In thisillustrated example, the protrusions 432 that are formed at the seam areformed in-line on the roll former after passing through several rollform dies on the roll form line. By roll forming the sheet stock 412 toachieve an intermediate cross-sectional shape of the beam 410 prior toforming protrusions 432, the protrusions can then be formed without arisk of being damaged or flattened from passing through roll form diesprior to being utilized at the weld seam. Specifically, as shown in FIG.19A, the outer edge portion 472 a of the sheet 412 that is used to formthe first tubular portion 414 of the beam 410 is spaced upward and awayfrom the desired landing surface 474 of the sheet to allow a laser beam434 to linearly access the landing surface 474 of the sheet 412 to formprotrusions 432.

As further shown in FIG. 19A, the rear corner 488 of the tubular portion414 may be used as a single articulation point on the sheet after theprotrusions 432 are formed. As shown in dashed lines, the sheet may bebent about the rear corner 488 to rotate the edge portion 472 a of thesheet down into abutting engagement with the protrusions 432 at thelanding surface 474. Accordingly, the cross-sectional shape may beformed to have essentially all desired shapes and formations of thefirst tubular portion 414 made in the outer section 472 of the metalsheet prior to forming the protrusions 432, such that only a finaladditional bend is needed at the rear corner 488 to close and completethe shape of the first tubular portion 414.

The protrusions 432 may be formed at a surface that corresponds with aportion of the sheet 412 that is desired to have a weld joint, such asat the landing surface 474 of the formed metal sheet 412 shown in FIG.19A. The landing surface 474 used to form the laser welded lap joint 436is deposed at a recessed area formed along the rear wall 426 at a cornerof the second tubular portion 416 adjacent to the center wall 418. Theprotrusions 432 may be formed when the metal sheet continuously passesthrough a laser head station that is arranged in-line on the rollformer, between roll form dies. To form the protrusions 432, the laserbeam 434 may be angled at a nearly perpendicular orientation relative tothe landing surface 474. The protrusions 432 formed in-line on the rollformer may be disposed at generally consistent intervals linearly alonga longitudinal extent of the sheet 412 and may otherwise be formed inthe same or similar manner to those shown in FIGS. 5A-5C and describedabove.

Prior to welding the seam of the first tubular portion 414 of the beam410, one or more forming rolls may further form the outer section 472 ofthe metal sheet 412 to bend and rotate the edge portion 472 a about therear corner 488 and place the outer edge 472 a in contact with the lineof protrusions 432 on the landing surface 474, as shown in FIG. 19A indashed lines. The line of contact of the protrusions 432 against theedge portion 472 a of the metal sheet 412 provides longitudinal spacingbetween the protrusions 432 that create ventilation openings for zincoxide fumes generated from welding to escape the interior of therespective tubular portion 414 of the beam 410.

With the outer portion 472 a near or in engagement with the landingsurface 474, the metal sheet 412 may enter a welding station that mayuse external mandrels to hold the shape of cross-section for welding,but otherwise be free of internal mandrels due to the cross-sectionalshape of the first tubular portion 414. As shown in dashed lines in FIG.19A, the weld joint 436 is formed via laser welding with a laser beam452 along the ventilation seam so as to provide a seam that is attachedand closed continuously along the length of the beam 410. When welding,the laser beam 452 may be disposed at the same or similar orientation tothe laser beam 434 used to form the protrusions 432. Due to theprotrusions 432 that form the ventilation openings, the weld joint 436may have a thickness, such as approximately between 50 micrometers and300 micrometers, which slightly separates a planar surface of the edgeportion 472 a of the outer section 472 from a planar surface of thelanding surface 474. The substantially perpendicular orientation of thelaser beam 452 further forms the weld joint 436 with a relatively narrowheat affect zone, such as approximately between 1 mm and 2 mm as shownin FIG. 7G.

With reference to FIG. 19B, after forming the weld joint 436, the sheet412 continues into a second series of forming rolls in stations thatsuccessively bend the other outer section 476 of the sheet 312 (FIG.19A) further toward the shape of the second tubular portion 416 of thebeam 410. The cross-sectional shape may be formed near, but prior toclosing a seam of the tubular portion 416 of the beam 410. At theintermediate cross-sectional shape shown in solid lines in FIG. 19B, theprotrusions 432 may be formed at the formed tip area of the outer edgeportion 476 a, whereby the protrusions 432 are formed after the shape ofthe edge portion 476 a is formed so as to reduce risk of damaging orflattening the protrusions. Specifically, as shown in FIG. 19B, theouter edge portion 476 a of the sheet 412 that is used to form thesecond tubular portion 416 of the beam 410 is spaced downward and awayfrom the desired landing surface 482 of the sheet to allow a laser beam484 to linearly and generally perpendicularly contact the surface of thetip area of the outer edge portion 476 a of the sheet 412 to form theprotrusions 432. Alternatively, it is contemplated that the protrusionsmay be formed at a lower area of the center wall on the opposing contactsurface of the resulting weld joint.

As further shown in FIG. 19B, the rear corner 486 of the second tubularportion 416 may be used as a single articulation point on the sheet. Thesheet may be bent about the rear corner 486 to rotate the formed edgeportion 476 a of the sheet down into abutting engagement with theprotrusions 432 formed at the landing surface 482, as shown in FIG. 19Bin dashed lines. Accordingly, the cross-sectional shape may be formed tohave essentially all desired shapes and formations of the second tubularportion 416 made in the outer section 476 of the metal sheet prior toforming the protrusions 432, such that only a final additional bend isneeded at the rear corner 486 to close and complete the shape of thesecond tubular portion 416. It is also contemplated that additional oralternative articulation points may be utilized on another example ofthe beam from that shown in FIGS. 19A and 19B, such as a beam with analternative cross-sectional shape or roll forming sequence.

As shown in FIG. 19B, the protrusions 432 may be formed when the metalsheet continuously passes through a laser head station that is arrangedin-line on the roll former, between roll form dies. The protrusions 432shown in FIG. 19B may again otherwise be formed in the same or similarmanner to those shown in FIGS. 5A-5C. Prior to welding the seam of thesecond tubular portion 416 of the beam 410, one or more forming rollsmay further form the outer section 476 of the metal sheet 412 to bendand rotate the edge portion 476 a about the rear corner 486 and placethe outer edge 476 a in contact with the landing surface 482 disposed atthe center wall 418, as shown in dashed lines in FIG. 19B. Again, theline of contact of the protrusions 432 on the edge portion 476 a of themetal sheet 412 against the center wall 418 provides longitudinalspacing between the protrusions 432 that create ventilation openings forzinc oxide fumes generated from welding the seam 438, such as with alaser beam 466, to escape the interior of the respective tubular portion416 of the beam 410. The ventilation openings allow fumes that wouldotherwise be trapped in an enclosed area of a tube to freely escape, soas to have a consistent weld that is free of gas openings or pocketsthat can form with pressured gases, such as zinc oxide gas.

The beam 410 may be made from a sheet 412 of steel material having athickness of 0.8 mm to 1.4 mm or approximately between 1 mm and 1.5 mm.Also, the sheet 412 may have a tensile strength of about 800 to 2000 MPa(i.e. about 120 to 290 ksi). However, it is contemplated that thepresent beam can be made of different materials, including AHSS(Advanced High Strength Steels) and that it can be made from a sheethaving a thickness of about 0.8 mm to 3.0 mm thick (or such as 0.8 mm to1.4 mm thickness), and can be made in different beam cross-sectionalsizes, such as about 80 mm to 150 mm high, and 30 mm to 60 mm deep, andhaving a variable sized length for the desired application.

With reference to FIGS. 20 and 20A, another example of a galvanizedmulti-tubular beam 510 is shown having two adjacent tubular portions514, 516 that share a common center wall 518 of the beam 510. The beam510 has a laser welded crevice joints 537 formed in the seams betweenthe center wall 518 and the front walls 520, 522 and the rear walls 524,526 to enclose the tubular portions 514, 516. The weld joints 537 formedvia laser welding along the ventilation seam by the laser beam 566 bydirecting the laser into the respective crevice seams generallyperpendicular to the orientation of the front and rear walls 520, 522,524, 526. Also protrusions may be provided in the crevice seams to formventilation openings for zinc oxide fumes generated from the welding toescape the interior of the tubular portions of the beam 510 upstream inthe roll former from the welding station.

For purposes of this disclosure, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the orientation shown in FIG. 1. However, it isto be understood that various alternative orientations may be provided,except where expressly specified to the contrary. It is also to beunderstood that the specific devices and processes illustrated in theattached drawings, and described in this specification are simplyexemplary embodiments of the inventive concepts defined in the appendedclaims. Hence, specific dimensions and other physical characteristicsrelating to the embodiments disclosed herein are not to be considered aslimiting, unless the claims expressly state otherwise.

Changes and modifications in the specifically described embodiments maybe carried out without departing from the principles of the presentinvention, which is intended to be limited only by the scope of theappended claims as interpreted according to the principles of patentlaw. The disclosure has been described in an illustrative manner, and itis to be understood that the terminology which has been used is intendedto be in the nature of words of description rather than of limitation.Many modifications and variations of the present disclosure are possiblein light of the above teachings, and the disclosure may be practicedotherwise than as specifically described.

The invention claimed is:
 1. A galvanized multi-tubular beam for avehicle structure or a bumper reinforcement, said galvanizedmulti-tubular beam manufactured by roll forming a galvanized metal sheetto form two adjacent tubular portions that share a common center wall ofthe beam, wherein outer sections of the metal sheet that form the twoadjacent tubular portions extend from opposing sides of a center sectionof the metal sheet that forms the common center wall of the beam, saidgalvanized multi-tubular beam comprising: an edge portion of one of theouter sections of the galvanized metal sheet attached to the centersection of the galvanized metal sheet at a weld joint; wherein the weldjoint has a thickness that separates a planar surface of the edgeportion from a planar surface of the center section; wherein thethickness of the weld joint is formed by a plurality of protrusions thatprotrude from the planar surface of the outer section or the centersection of the metal sheet; wherein the plurality of protrusions eachcomprise a recessed portion protruding into the planar surface and araised portion protruding from the planar surface; and wherein, whenwelding the weld joint, a longitudinal spacing between the plurality ofprotrusions provides ventilation openings for zinc oxide fumes generatedfrom the welding to escape an interior of the respective tubular portionof the beam.
 2. The galvanized multi-tubular beam of claim 1, whereinthe weld joint extends continuously along the beam to enclose theinterior of the respective tubular portion of the beam.
 3. Thegalvanized multi-tubular beam of claim 1, wherein the raised portionprotrudes from the planar surface a height generally equal to a width ofthe ventilation openings.
 4. The galvanized multi-tubular beam of claim3, wherein the plurality of protrusions are spaced at consistentintervals, and wherein the weld joint interconnects the plurality ofprotrusions.
 5. The galvanized multi-tubular beam of claim 1, whereinthe weld joint has a narrow heat affect zone of approximately between 1mm and 2 mm.
 6. The galvanized multi-tubular beam of claim 1, wherein asecond edge portion of the galvanized metal sheet is attached at a sidewall of the tubular portion of the beam that is generally perpendicularto the center wall of the beam.
 7. The galvanized multi-tubular beam ofclaim 6, wherein the second edge portion and the side wall are attachedtogether at a laser welded lap joint.
 8. The galvanized multi-tubularbeam of claim 7, wherein the laser welded lap joint includes a secondthickness that separates a planar surface of the second edge portionfrom a planar surface of the side wall, and wherein the thickness of theweld joint is formed by a second plurality of protrusions that protrudefrom the planar surface of the second edge portion or the side wall,such that when welding the lap joint zinc oxide fumes escape theinterior of the respective tubular portion of the beam through ventopenings formed by the second plurality of protrusions.
 9. Thegalvanized multi-tubular beam of claim 1, wherein a separation betweenthe edge portion and the center section that is formed at the weld jointis approximately between 50 micrometers and 300 micrometers.
 10. Thegalvanized multi-tubular beam of claim 1, wherein a length of each ofthe plurality of protrusions is approximately between 2 mm and 5 mm. 11.The galvanized multi-tubular beam of claim 1, wherein a thickness of themetal sheet is approximately between 1 mm and 1.5 mm.
 12. A method ofcontinuously forming a galvanized reinforcement beam, said methodcomprising the steps of: uncoiling a roll of galvanized sheet stock in agenerally horizontal plane; roll forming the sheet stock through a rollformer comprising a set of a plurality of roll stations to form atubular shape with an edge section of the sheet stock in contact with anintermediate section of the sheet stock; forming protrusions over anupper surface of the sheet stock as the sheet stock moves in-line withthe roll former; wherein at least one of the edge section or theintermediate section of the sheet stock includes the protrusions, andwherein the protrusions form venting gaps between the edge section andthe intermediate section of the sheet stock; and laser welding an edgeportion to an intermediate portion of the sheet stock at a laser headstation to continuously form a weld joint, wherein zinc oxide gasgenerated from the welding is permitted to escape an interior of thetubular shape through the venting gaps.
 13. The method of claim 12,wherein the protrusions are spaced at generally consistent intervals andlinearly disposed over the upper surface of the sheet stock.
 14. Themethod of claim 12, wherein the protrusions each comprise a raisedportion that protrudes from the upper surface a height generally equalto a width of the venting gaps.
 15. The method of claim 12, wherein theprotrusions are formed with at least one of laser dimpling, mechanicaldeformation, electrospark deposition, or additive material.
 16. Themethod of claim 12, wherein the sheet stock is uncoiled, roll formed,and welded in a longitudinal direction at a generally constant speed.17. The method of claim 12, wherein the protrusions are continuouslyformed at a station interposed in the set of the plurality of rollstations.
 18. The method of claim 17, wherein the protrusions are formedwith a laser head station disposed between a first station and a laststation of the set of the plurality of roll stations, so as to form theprotrusions during the roll forming process.
 19. A method ofcontinuously forming a galvanized reinforcement beam, said methodcomprising the steps of: uncoiling a roll of galvanized sheet stock in agenerally horizontal plane; feeding the sheet stock from the roll to aroll former in the generally horizontal plane; roll forming the sheetstock in the roll former to form a tubular shape with the protrusionsabutting a surface of the sheet stock to form venting gaps; formingprotrusions over an upper surface of the sheet stock as the sheet stockmoves in-line with the roll former; and laser welding the sheet stock atthe protrusions to continuously form a weld joint, wherein zinc oxidegas generated from the welding is permitted to escape an interior of thetubular shape through the venting gaps.
 20. A galvanized multi-tubularbeam, said galvanized multi-tubular beam manufactured by roll forming agalvanized metal sheet to form two adjacent tubular portions that sharea common center wall of the beam, said galvanized multi-tubular beamcomprising: an edge portion of an outer section of the galvanized metalsheet attached via a weld joint to a reinforcement rib formed at centersection of the galvanized metal sheet, wherein the edge portion of thegalvanized metal sheet forms the common center wall of the beam; whereinthe weld joint has a thickness that separates a planar surface of theedge portion from a planar surface of the reinforcement rib; wherein thethickness of the weld joint is formed by a plurality of protrusions thatprotrude from the planar surface of at least one of the edge portion orthe reinforcement rib; wherein the plurality of protrusions eachcomprise a recessed portion protruding into the planar surface and araised portion protruding from the planar surface; and wherein, whenwelding the weld joint, a longitudinal spacing between the plurality ofprotrusions provides ventilation openings for zinc oxide fumes generatedfrom the welding to escape an interior of the respective tubular portionof the beam.